package com.juc.unsafe;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.UUID;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * 同理可证 ： ConcurrentModificationException
 * //1、Set<String> set = Collections.synchronizedSet(new HashSet<>());
 * //2、 Set<String> set = new CopyOnWriteArraySet<>();
 */
public class SetTest {
    public static void main(String[] args) {
        //Set<String> set = new HashSet<>();
        //1 Collections.synchronizedSet(new HashSet<>());
        //Set<String> set = Collections.synchronizedSet(new HashSet<>());
        Set<String> set = new CopyOnWriteArraySet<>();
        for (int i = 0; i <= 30; i++) {
            new Thread(()->{
              set.add(UUID.randomUUID().toString().substring(0,5));
                System.out.println(set);
            }).start();
        }
    }
}
